Policyholders' Liabilities (Policyholders' Account Balances) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Liability for Policyholders' Account Balances, by Product Segment [Line Items]
Total policyholders’ account balances	$ 4,736,889	$ 2,416,125
Interest-sensitive life contracts
Liability for Policyholders' Account Balances, by Product Segment [Line Items]
Total policyholders’ account balances	15,666	15,832
Individual annuities
Liability for Policyholders' Account Balances, by Product Segment [Line Items]
Total policyholders’ account balances	1,441,126	1,337,876
Guaranteed interest accounts
Liability for Policyholders' Account Balances, by Product Segment [Line Items]
Total policyholders’ account balances	893,419	1,062,417
Assumed | Pruco Life
Liability for Policyholders' Account Balances, by Product Segment [Line Items]
Total policyholders’ account balances	$ 2,386,678	$ 0